《WSN-无线传感器网络》复习提纲-3.0版

1、精品word可编辑资料- - - - - - - - - - - - -1.2 application examples1.4 application examples 1.disaster relief applications2. environment control and biodiversity mapping3. intelligent buildings 4.facility management5.machine surveillance and preventive maintenance 6.percision agriculture7.medicine and heal

2、th care 8.logistics9.telematicsunderstand the challenges of wsns:1.4 wsn 的挑战性1.4 challenges for wsns1.4.1 characteristic requirements：要求的特性1. type of service2. quality of service3. fault tolerance4. lifetime5. scalability6. wide range of densities7. programmability8. maintainability1.4.2 required me

3、chanisms:要求机制some of the mechanisms that will form typical parts of wsns are:1. multihop wireless communication2. energy-efficient operation3. auto-configuration4. collaboration and in-network processing5. data centric6. locality7. exploit trade-offsunderstand the differencesbetween wsns and other n

4、etworks:第 20 页，共 20 页- - - - - - - - - -1.5 为什么说传感器是不同的1.5 why are sensor networks different.1.5.1 mobile ad hoc networks and wireless sensor networks（移动 ad hoc 网络与无线传感器网络）1. applications, equipment: manets more powerful read: expensive equipment assumed, often “ humanin the loop ”-type applications

5、, higher data rates, more resources2. application-specif:icwsns depend much stronger on application specifics; manets comparably uniform3. environment interactio:ncore of wsn, absent in manet4. scale: wsn might be much larger although contestable5. energy: wsn tighter requirements, maintenance issue

6、s6. dependability/qos: in wsn, individual node may be dispensable network matters, qos different because of different applications7. data centricvs. id-centric networking8. mobility: different mobility patterns like in wsn, sinks might be mobile, usual nodes static1.5.2 wireless fieldbuses and wsn（s

7、differences：现场总线与无线传感器网络）1. scalewsn often intended for larger scale2. real-time wsn usually notintendedtoprovidehard real-time guarantees as attempted by fieldbusesunderstand theenablingtechnologies forwsns application1.6 无线传感器网络的技术要求1.miniaturization of hardware 2 processing munication1.2 applicat

8、ion examples应:用领域disaster relief applications, environment control and biodiversity mapping, intelligent buildings, facility management, machine surveillance and preventive maintenance, precision agriculture, medicine and health care, logistics, telematics.1.3 types of application:区分应用类型1. event det

9、ection2. periodic measurements3. function approximation and edge detection4. tracking其次章： 2.1.1 ，2.1.4,2.1.5， p37,43,2.2.5,2.3.2,2.3.5,basic requirement:master the hardware components of sensor nodes2.1 节点的硬件组成2.1 hardware components: 硬件组成部分main components of a wsn node controllercommunication devic

10、es sensors/actuators memorypower supply2.1.4 communication device transceiver operational states收:发机的四个状态transceivers can be put into different operationalstates, typically:transmit-in the transmit state, the transmit part of the transceiver is active and the antenna radiates energy.receive- in the

11、receive state the receive part is active.idle ready to receive, but not doing sosome functions in hardware can be switched off, reducing energy consumption a littlesleepsignificant parts of the transceiver are switched offnot able to immediately receive somethingrecovery timeand startup energyto lea

12、ve sleep state can be significant无线传感器的微掌握器也有三个状态（活跃期，闲暇期，睡眠期），两者有区分！2.1.5 sensors: 传感器的分类passive, omnidirectional sensors被动全向传感器 温湿度传感器等typical examples for such sensors include thermometer, light sensors, vibrationmicrophones,humidity,mechanical stress ortensioninmaterials, chemical sensors sensit

13、ive forgivensubstances, smoke detectors, air pressure, and so on.passive, narrow-beam sensors被动、窄束 照相机等a typical example is a camera, which can“ take measurements” in a given direction, but has to be rotated if need be.active sensors 主动 雷达 声呐等for example, a sonar or radar sensor or some types of sei

14、smic sensors, which generate shock waves by small explosions.understand the energy consumption of componentmodule2.2 energy consumption of sensor nodes留意区分每一个硬件部分的能量分析， 哪一部分是比较针对微掌握器的能量分析（ whether put into sleep mode should be taken to reduce power consumption）、哪一部分是比较针对收发机、哪一部分是比较针对运算传输等节省能量时会用到：调整

15、掌握器的功率消耗时 dvs收发机能耗，与调制结合， dms（动态调制调整）（从 dvs动身的） dcs动态码调整dmcs动态调制码调整运算和通信之间能量消耗的关系a controller, typical states are“ active”,“ idle ”mo, daenmd co“ulsdletuerpn ”; a radiotransmitter, receiver, or both on or off; sensors and memory could also be turned on or off. the usual terminology is to speak of a

16、“ deeper s”leep state if less power is consumed；耗能主体 1.controller 2.radio frontends 3.memory2.2.3 memory 储备器on-chip memory of a microcontroller and flashmemory2.3 节点的操作系统与运行环境2.3 operating systems and execution environments无线传感器网络 os基于大事的，而非基于进程的operating system: event-based programming基于大事protocol

17、stacks : component-based基于部件typical os: tiny osevent-based programmingthe idea is to embrace the reactive nature of a wsn node and integrate it into the design of the operating system. the system essentially waits for any event to happen, where an event typically can be the availability of data from

18、 a sensor,the arrival of a packet, or the expiration of a timer. such an event is then handled by ashort sequence of instructions that only stores the fact that this event has occurred and stores the necessaryinformation for example, a byte arriving for a packet or the sensor s valuesomewhere. the a

19、ctual processing of this information is not done in these event handler routines, but separately, decoupled from the actual appearance of events. thisevent-based programming353 model is sketched in figure 2.8.understand properties of different nodes.2.4 传感器节点的一些例子第三章选、判、填basic requirement:understand

20、 the sensor network scenarios3.1 传感器网络工作场景3.1.1 types of sources and sink信s宿a source is any entity in the network that can provide information, this is, typically a sensor node; it could also be an actuator node that provides feedback about an operation.a sink is entity where information is required

21、. it belong to the sensor network ; be just another sensor/actuator node; be an entity outside this network.3.1.2 multihop networksbecause of this limited distances. store and forward障. 碍物 obstacle3.1.4 three types of mobilitynode mobility: the wireless sensor nodes themselves can be mobile. environ

22、mental control will not happen.sink mobility: the information sinks can be mobile. while this can be aspecial case of node mobility. the important aspect is the mobility of an information sink that is not part of the sensor network.event mobility: in applications like event detection and in particul

23、ar in tracking applications, the cause of the events or the objects to be tracked can be mobile.master the design principles of wsn：s3.3 wsn设计原就3.3 design principles for wsnsappropriate qos support, energy efficiency, and scalability are important design and optimization goals for wireless sensor ne

24、tworks.在构建 wsn结构时的设计原就：分布式组织 distributed organization网络内部处理自适应的保真度与精度in-networkprocessing adaptivefidelityand accuracy以数据为中心data centricity利用位置信息exploit location information利用主动模式exploit activity patterns利用多样性 exploit heterogeneity基于部件的协议栈与层的优化component-basedprotocolstacks andcross-layer oprimizatio

25、n分布式组织，3.3.1 distributed organizationboth the scalability and the robustness optimization goal, and to some degree also the other goals, make it imperative to organize the network in a distributed fashion. that means that there should be no centralized entity in chargesuch an entity could, for examp

26、le, control medium access or make routing decisions, similar tothetasks performedby a base stationincellularmobilenetworks.thedisadvantagesof such a centralized approach are obvious as it introduces exposed points of failure and is difficult to implement in a radio network, where participants onlyha

27、vea limitedcommunicationrange.rather, thewsns nodes should cooperatively organize the network, using distributedalgorithms and protocols. self-organizationis a commonly used term for this principle.when organizing a network in a distributed fashion, it is necessary to be aware of potential shortcomi

28、ngs of this approach. in many circumstances, a centralized approach can produce solutions that perform better or require less resources in particular, energy. to combine the advantages, one possibility is to use centralized principles in a localized fashion by dynamically electing, out of the set of

29、 equal nodes, specific nodes that assume the responsibilities of a centralized agent, for example, to organize medium access. such elections result in a hierarchy, which has to be dynamic: the election process should be repeated continuously lest the resources of the elected nodes be overtaxed, the

30、elected node runs out of energy, and the robustness disadvantages of such even only localized hierarchies manifest themselves. the particular election rules and triggering conditions for reelection vary considerably, depending on the purpose for which these hierarchies are used.网内处理：3.3.2 in-network

31、 processing网络内部处理1. aggregation2. distributed source coding and distributed compression3. distributed and collaborative signal processing4. mobile code/agent-based networkingdistributed source coding and distributed compression聚合 aggregation 搞清原理 网内信息处理aggregationp683.3.4 data centriciy1. address da

32、ta, note nodes2. implementation options for data-centric networking1. overlay networks and distributed hash tablespeer-to-peer2. publish/subscribe any node interested in a given kind of data can subscribe to it, and any node can publish data, along with information abut its kind as well.3. databases

33、数 据库understand the gateway concepts.3.5 网关的概念3.5 gateway conceptsprovides the physical connection to the internet 供应物理连接regard a gateway as a simple router between internet and sensor network因特网与传感器网络之间的简洁路由第四章 物理层masterthewireless channel andcommunication fundamentals,4.2 无线信道的通信基础4.2.1 frequency a

34、llocation frequency band ism433-464mhzeurope 902-928mhzamericas2.4-2.5ghzwlan/wpan5.725-5.875ghz wlan4.2.2 区分 symbol rate 和 data ratesymbol ratethe symbol rate is the inverse of the symbol duration; for binary modulation, it is also calledbit rate.data ratethe data rate is the rate in bit per second

35、 that the modulator can accept for transmission; it is thus the rate by which a user can transmit binary data. for binary modulation, bit rate and data rate are the same and often the term bit rate is sloppily used to denote the data rate.4.2.3 path loss and attenuation 路径损耗和衰减wireless waveforms pro

36、pagating through free space are subject to a distance-dependent loss of power, called path loss. attenuation because of transmitted in some media, not in the vacuum.p97wsn信道模型wsn-specific channel modelssince in addition the data rates are moderate, it is reasonable to expect frequency nonselective f

37、ading channels with noise and a low-to-negligible degree of isi.accordingly, no special provisions against isi like equalizers are needed典.模型：频率非挑选性衰弱信道，并且可以忽视符号间干扰4.2.3 wave propagation effects and noise4.2.4 channel models型的信道understand physical layerandtransceiver designconsiderations in wsns.4.3

38、 wsn 物理层和收发机设计考虑4.3.1能量使用的特点（作业） ：辐射的能量的影响；发射能量和接收能量的比较；启动能量、启动时间the radiated energy is smal；lthe overall transceiver rf front end and basebandpart consumes much more energy than is actually radiated辐射能量较小；for small transmit powers the transmit and receive modes consume more or less the same power；i

39、t is even possible that reception requires more power thantransmission; depending on the transceiver architecture, the idle mode s powconsumption can be less or in the same range as the receive powe；r 基本相同 startup energy/startup time， a transceiver has to spend upon waking up from sleep mode；startup

40、 energy/time penalty can be high4.3.3dynamic modulation scaling 108 页动态调制调整：原理假如增加 b 和 m 的值，比特推迟会减小，每个比特的能量消耗主要取决于m，与 b 也有关，事实上，对于特殊的参数选取，已经说明，当符号率最大时，每个比特消耗的能量和每个比特的推迟是最小的；分组数增加，m 增加antenna第五章basic requirement:masterthe fundamentals of mac protocols5.1 无线 mac 协议的基础学问113 隐匿终端、暴露终端the hidden-terminal

41、 problem occurs specifically for the class of carrier sense multiple access csma protocols, where a node senses the medium before starting to transmit a packet.using simple csma in anexposed terminal scenaritohus leads to needless waiting.5.1.2 114 页 mac 协议的分类固定配置协议fixed assignment protocols按要求配置协议d

42、emand assignment protocols随机接入协议random access protocols116 解决隐匿终端的手段 2 个the busy-tone solution 忙音技术the rts/cts handshake握手技术5.1.2 important classes of mac protocols1. fixed assignment protocols 固定配置协议 tdma fdma cdma sdma不 能2. demand assignment protocols 按需安排的协议 leach3. random access protocols 随机接入协议

43、 aloha slotted alohahigher through put csma nonpersistent csma backoff algorithm busy-tone solution解决了隐匿终端和暴露终端的问题，与数据传输距离相同之处能侦听到忙音信号；rts/cts握手方法 基于 wacaw协议 一个信道两个掌握分组rts恳求发送 cts清除发送 data 数据 ack 确认 将一个较大的分组拆分为几个较小的分组 保证 cts 比 rts 长119 5.1.3mac 层的能量问题collisions 碰撞wasted effort when two packets colli

44、defixed assignment/tdma or demand assignment protocols ， csma protocolsoverhearing 偷听waste effort in receiving a packet destined for another node idle listening 闲暇监听 sitting idly and trying to receive when nobody is sendingtdma-based protocolsprotocol overhead协议开销 protocol overhead is induced by mac

45、-related control frames like, for example, rts and cts packets or request packets in demand assignment protocols,understandthe low duty cycle protocolsand wakeup concepts,5.2 低占空比协议与唤醒的概念每个协议针对能量问题的算法的区分，最突出，最不同的点s-mac smacs占空比=侦听阶段 / 唤醒周期avoid spending much time in the idle state and to reduce the

46、communication activities of a sensor node to a minimum.大部分时间处于休眠状态并周期性的被唤醒来接收来自其他节点的分组periodic wakeup 周期性唤醒 把握发送目标的监听时段5.2.4 wakeup radio concepts无线唤醒的概念节点发送或者接受或者休眠 不存在闲暇状态 fdma 低功耗唤醒收发机处于常常工作的状态 信道闲暇 收到唤醒信号 唤醒数据收发机 有通信量自适应功能负载增加 mac 越来越活跃understand contention and schedule based protocols,5.3 基于竞争的

47、协议5.3哪些是基于竞争的协议contention-based aloha、csma哪些基于调度表协议 schedule-based leach smacs trama哪些基于安排的协议5.4 基于时间的协议5.4.1leach自适应的低功耗的分簇算法leach协议将一个基于 tdma的 mac 协议与聚类协议和一个简洁的“路由”协议集成在一起分簇 簇头节点 负责确定和保护 tdma 时间表 对成员节点安排 tdma 时隙 能量消耗大 每个成员节点轮番担任簇头节点 簇头节点在网络节点中所占的百分比是一个有用的网络参数重点csma rps ctsmasterthe ieee 802.15.4 m

48、ac protocol.5.5.1network architecture and types/roles of nodes一个标准的 mac 层分为两种不同的节点1. 全功能设备 ffd pan网络和谐器 简洁和谐器 设备 三种功能2. 精简功能设备 rfd 只用作设备一个设备必需与一个和谐器一起工作并仅与其进行通信构成一个星状网络和谐器可以工作于对等模式和谐器完成四个任务超帧的结构 ieee 802.15.4活跃时段不活跃时段信标 竞争介入时段保证时隙节点在 cap时段必需发送数据分组或治理掌握分组时采纳slotted csma-ca protocolcsma protocol区分 不包含

49、关于隐匿终端的规定使用随机推迟使用带有碰撞防止的csma 协议 回退时段basic requirement:understand therole and significance of thetime synchronization problem,8.1 懂得时间同步问题的概念和意义202各个时间的概念物理时间 大多数应用和协议都要求物理时间规律时间 分布式系统中大事发生的次序关系physical time= wall clock time, real-time, coordinated universal time utc logical time：allows to determine

50、the ordering of events in a distributed system but does not necessarily show any correspondence to real time8.1.2 node clocks and the problem of accuracy 203 external synchronization:synchronization with external real time scale like utcnodes i=1, ., n are accurate at time t within bound d when |lit

51、 t|<d for all ihence, at least one node must have access to the external time scale internal synchronizationno external timescale, nodes must agree on common timenodes i=1, ., n agree on time within bound d when |lit ljt|<d for all i,jmetrics:precision: maximum synchronization error for determ

52、inistic algorithms, error mean / stddev / quantiles for stochastic onesenergy costse,.g. # of exchanged packets, computational costsmemory requirementsfault tolerance: what happens when nodes die.8.2 基于发送 / 接收的时间同步协议8.2 protocols based on sender/receiver synchronization207基于公共步骤 1.成对同步 2.全网同步lightwe

53、ight time synchronization protocol lts比对同步协议完成两个相邻节点的同步建立一个从参考节点到全部节点的层次最少的生成树发送接收的同步运算方法运算题作业分布式多跳 lts 不需要构造生成树每个节点需要知道很多参考节点并沿着适当的路径到达他们 这些参考节点的责任就是周期性的启动再同步8.2.3 time-sync for sensor networks tpsn非对称 i 可以与 j 但是反过来不行8.3 基于接收 / 接收的时间同步协议8.3.1 reference broadcast synchronizationrb参s考广播同步多跳范畴内的网络同步ne

54、twork synchronization over multiple hops多广播域 rbs 不断变换时间确保最终到达信宿的时间是精确的以 utc时间表示basic requirement:understandthepropertiesoflocalizationand positioning procedures,9.1 9.2 wsn定位网络的特点和方法9.1 properties of localization and positioning proceduresphysical position versus symbolic location absolute versus re

55、lative coordinates localized versus centralized computation accuracy and precisionaccuracy：估量值与实际值的最大距离precision：达到精确性的百分比scale limitations costs9.2 定位的三种方法possible approaches1. proximity 利用相邻节点的信息进行定位2.trilateration and triangulation 三边定位和三角定位determining distances三种测距方法rssi toa tdoa 3.scene analysi

56、s情形分析9.3 mathematical basics for the lateration problem 测边定位understand the differences between the single-hop and multihop localizations,9.4 9.5 单跳定位与多跳定位的区分9.4.6 approximate point in triangle 近似三角形内点测试法对于全部的邻居节点， 假如三个顶点到邻居节点的距离没有同时更近或更远，那么未知节点在三角形内，否就在三角形外；understand the impact of anchor placement.9.5dv hop：9.5.2p245count number of hops, ass